1. Field of the Invention
The present invention relates generally to a locking mechanism suitable for use with a body and a lid which are arranged to lock into each other and, more particularly, to a locking mechanism of the type which is used with a protector for wire harnesses so as to secure the lid of the protector to the body thereof.
2. Description of the Related Art
FIGS. 5 and 6 show a conventional example of such a locking mechanism which is provided in a protector for protecting wire harnesses used for wiring electrical equipment in an automobile or the like. This kind of locking mechanism is described in, for example, the specification of Japanese Utility Model Laid-open No. 13931310-1988. In the figures, a protector body 1 has a bottom la and side walls 1b formed on the opposite sides thereof, forming a U-shaped configuration in cross section, and a space for accommodating a plurality of wire harnesses 7 is formed in the protector body 1. A lid 2 has a lid portion 2a and side portions 2b whose height is small compared with that of the side walls 1b, and forms a U-shaped configuration in cross section. Engagement projections 3 are formed in the vicinity of the engagement edge portion of each of the side walls 1b of the protector body 1, while engagement holes 4 are formed in the lid 2 at locations corresponding to the engagement projections 3 so that the engagement projections 3 can be fit into the corresponding engagement holes 4. The wire harnesses 7 are accommodated in the protector body 1, and the lid 2 is secured to the protector body 1 by a tape 8.
FIG. 5 is a perspective view showing the essential portion of the locking mechanism composed of the engagement projections 3 formed on the protector body 1 and the engagement holes 4 formed in the lid 2. Holding plates 6 are fixed to the lid portion 2a of the lid 2 so as to force the engagement projections 3, formed on the side walls 1b of the protector body 1, toward the corresponding engagement holes 4 by way of the adjacent side walls 1b.
Since such a protector usually accommodates a multiplicity of wire harnesses 7 which are heavy compared with the protector, there is a tendency for a force derived from the weight of the wire harnesses 7 to be applied to locking portions at which the protector body 1 and the lid 2 are engaged with each other. FIG. 6 is a cross-sectional view, taken along line VI--VI of FIG. 5, showing one of the locking portions. As illustrated, if a force as indicated by an arrow F is applied to the lid 2 when the body 1 is engaged with the lid 2, the lid portion 2a and the holding plate 6 tend to be displaced toward the position shown by phantom lines. As a result, a gap is formed at a point A' at which the lid 2 should be kept in contact with the inner edge of the side wall 1b. It follows, therefore, that the engagement projection, 3 of the side wall 1b of the protector body 1 is engaged with the lid 2 at a hook 3' alone. In consequence, it is likely that the engagement projection 3 is disengaged from the engagement hole 4.
To eliminate the likelihood of such disengagement, as shown in FIG. 5, it has been necessary to engage the lid 2 with the protector body 1 and then to fix them by winding the tape 8 therearound.